You can see most of the performance above, and another bit below. This all took place on the sixth date of Rodgers' 14-date Free Spirit tour, which as you can probably guess by the name is celebrating the music of his first band, Free.

As LedZepNews explains, Plant and Johnson were recently seen filming an episode of Johnson's 'A Life on the Road' television series. Johnson was forced to leave AC/DC's most recent tour in March of 2016 after doctors warned him that he risked permanent hearing loss if he continued performing with the group live.

Last June, Johnson met with the inventor of a new type of in-ear monitors that could theoretically allow him to return to the stage without further hearing damage, and reported that he "was really moved and amazed to be able to hear music again like I haven’t heard for several years now." However, the technology reportedly is still in development and not ready for everyday use. It is not known what hearing protection precautions Johnson took before performing with Rodgers this evening.